Stencil duplicating inks



Patented June 12, 1951 STENCILDIIPLICATING INKS Thomas Seal Chambers and -'I tobert-'1h0mps0n Florence, --Chicago, :IlL, assignors to A. BrDick .Company, Chicago,:'Ill., acorporation of Illinois iNoDrawilig. ApplicationApril 16,1949,

Serial No. 885043 :8.Claims. (Cl. 26092913) "This invention relatestowater-base stencil duplicating inks for use with rotary stencil duplieating machines or for use in otherstencilling operations wherein ink is transferred through a stencil to an impression medium.

In a stencil'duplicating machine of'the rotary type-ink is supplied inconti-nueus;fashionto an ink pad, other like reservoir or distributing medium. After uniform distribution therein, inkis transmitted through the openings of astehcil to the impression medium, chiefly in response-to forces developed-attire point of-contactbetween a rotating cylinder and the impression =roller. For the mostpart, dryingof-theappliedink-occurs'by absorption of the vehicle-or carrierdnto the pores of the impression-medium or into the interstices 'between the fibers of which the impressionmedium may be 'formed.

The characteristics desirable in a, stencil duplieating ink are manifold and-in manyrespects, non-analogous to ink compositions commonly usedfor printing or writing. For-exampleyin order to functionproperly in'the duplicating machineythe inkshould have sufiicient apparent body to'minimize leakage from the cylinder ;and the pad and to prevent-flooding of the; stencil. 'Qn'theother hand, to produoeuniform and good. copy, it should-have sufiicientflow ofa desiredcharacter toeffect satisfactory transmission through ,the stencil to "the impression medium anditozenable uniform and rapid distribution;;of the ink throughout the ink pad. Tl'lfllflk' should be sufficiently slow-drying while in the machine to minimize premature hardening on" the ink pad or clogging ofithe stencil openings. -At;the-same time, i it should be quick drying when applied-to the in pression medium; otherwise, it would-be necessary'to resort'to special devicesand costly practices in order to handle copy Within a reasonable time-and eliminate setoffi The i-nk should dry-without featheringmvithout givingamoily or coloredletter out-line or --ha'lo, and it should-not give "show-'t-hroug-h-, which ma-y -be- 'defined :as visi-bilitydromthe oppositeside of thedmpression-mediu-m. --'I-he ink-should :also be stableand nonecorro'si-ve to thermaohine parts "with: which it might come iii-contact. Upon-drying, itshould beresistant to "moisure; the common solvents, and other substances with "which the copy --might come in-=contact.

I o the-:bestaof: our knowledge; stencil duplicatingiinks heretofore -produced fail to meet these requirements. 1: Suchiailure maysbe attributed-in part to the formulation of stencil duplicating inks with large amounts of oil, the greater portionof which is of the non-dryingtype such as castor oil palm oil, cocoanut oil, and the like. Qils in suchlarge proportion and of a non-drying character permit a highly objectionable degree of setofi and smear unless special devicesgare used-in handling the copy. The commonest devicetocope with this problem is the costly and awkward practice of slip-sheeting; thatis, the insertion of interlayer sheets between successive copies as the are duplicated. -The problem inay bealleviated to a limited extent by using, as the impression medium, highly absorbent paper stock which rapidly distributes the vehicle but then the use Of highlyabsorbent impression medium makes. it practically impossible to obtain sharply defined copy because of feathering of the ink.

.High-oil content is directly responsiblefor the presence of objectionable oily letterfoutlineQor halo in copy prepared with; oil base inks. S te cilduplication with oil base ink is further-burdened by the fact that its use is limited to impression media of a highly absorbent nature and is not usedsuccessfully. with hard orhighly filied p p s a card, ledger, be ena e stock- .Qi hazs zem ls n inks areiorm wi ;1es oil'to relieve some of the objectionable'ieatures o twe nm sio i ksb ma or the 1-m tations inherent in-the oils still remain. Emulsion inks present other operating .problems' becausethey have-. less stabilityand often'separate atlsome-stage priorto transmission through the stenciLwherebythe. ink pad ,or the stencil 'or both become clogged andprevent uniform ink distributiorrto complicate. theproduction of good copy. In addition, the inner phase. of theinkemulsion frequently contains sulfonated. glyceridesthat'are corro'sivetomachine. parts or other elementswith which the ink might be associated.

it is an object of this invention to produce a stencil duplicating ink thatis not subjectto the objections to prior duplicating inks.

aMorespecificallm-it is an-object of this invention toe-produce astencil duplicatingink that is 3 eating machines and in the production of copy of good quality.

A further object is to produce an oil-free stencil duplicating ink which has the desired balance of slow drying while in the stencil duplicating machine and quick drying upon transmission to the impression medium.

A still further object is to produce a stencil duplicating ink which may be used for duplication on hard, filled, or highly finished impression media, stocks upon which stencil duplication without slip-sheeting was practically impossible with stencil duplicating oil base inks heretofore used.

Another object is to produce a stencil duplicating ink which is quick drying to permit handling of the copy almost immediately after duplicating without fear of setoff or smearing, and which, upon drying, becomes substantially impervious to moisture, many hydrocarbons and solvents with which the copy might come in contact.

A still further object is to produce a stencil duplicating ink which is substantially non-corrosive, non-fiammable, stable, safe and easy to manufacture and handle.

A very important object of this invention is to formulate a water base stencil duplicating ink without oils. We achieve these characteristics with a formulation constituted with water as .the major diluent and the vehicle for the tincwater base is used torial agent. The term because Water is present as a major constituent; often the water content is as high as 75 or 85 percent.

Body or flow of the desired character is derived primarily from the incorporation into the ink composition of high molecular weight sub" stances which are soluble in water or dilute aqueous alkaline solutions. The high molecular weight substance, in reality, serves two separate functions. It serves as the bodying agent in the ink composition; and it serves, subsequently, as an adherent base upon drying.

Suitable water base stencil duplicating inks embodying features of our invention have a 4 is greater than 1000. Representative of suitable bodying agents of high molecular Weight are the hydroxy resinous materials, such as polyvinyl alcohols; hydroxylated cellulose ether derivatives, including hydroxy ethyl cellulose, partially alkylated cellulose derivatives, such as methyl cellulose and ethyl cellulose having about one-third of the hydroXy groups alkylated, or water soluble salts of carboxy methyl cellulose or ammonium carboxy celluloses. Use may also be made of other relatively Water soluble high molecular weight compounds, such as the carbohydrates, including starches, and certain sugars, dextrin, and the like; proteins, including gelatin, glue, casein and the like; polyethylene glycols; and resin forming material reacted to an intermediate stage of polymeric growth, such as the water soluble A-stage phenol-aldehyde resins wherein the phenolic component is of the type phenol, cresol, xylenol and resorcinol and the aldehyde is of the type formaldehyde, the intermediate being constituted primarily of phenol alcohols; or nitrogenous resin forming materials such as urea, melamine and guanidine reacted with an aldehyde to an intermediate stage of polymeric growth to provide water soluble substances such as methylol ureas. Characteristic of many of these materials are the free hydroxy and/or amino groups which influence water solubility and enable subsequent insolubilization by reaction With such materials as glycxal.

Proper concentration of the high molecular weight substance in the ink composition required to impart the desired flow characteristics depends on its average molecular weight, the arrangement and type of constituent groups of capable of giving a viscosity equivalent to 35-150 measurable viscosity that is much lower than the viscosity of oil base inks or oil emulsion inks operable under corresponding conditions. Viscosity can be used as a measure for certain flow characteristics; yet, we find it impractical presently to define the desired flow characteristics rigidly and exclusively in terms of viscosity. When measured by a Stormer Viscosirneter operating under a 200 gram load at 20 C. with a standard cup having a thermometer well and a center bafiie, suitable water base inks may give a reading between 35 and 150 seconds; whereas, many oil base inks give a reading between 400-500 seconds, and many oil emulsion inks give a reading between 325 and 400 seconds. The lower viscosity permissible with water base inks of the type produced by this invention favors more rapid and uniform distribution of the ink throughout the ink pad and greater ease of operation in the duplicating process.

As the high molecular weight substance, use may be made of organic materials capable of increasing the viscosity or body of the aqueous medium in which it is dissolved. Ordinarily, such characteristics are secured by the use of organic compounds and polymers having at least 30 carbon atom-s, mostly in chainlike arrangement; more often, suitable compounds are measured by their average molecular weight which ordinarily seconds measured with a Stormer viscosimeter under the described conditions. In actual practice, the desired viscosity may be secured with about 3-20 percent polyvinyl alcohol (depending on the molecular Weight of the original polyvinyl ing machines in the course of developments, and

the amount of bodying agent may change accordingly without departing from the spirit of the invention.

As tinctorial agents, dyes or pigments soluble or dispersible in the largely aqueous vehicle may be used. Representative of the class of dyes having the desired solubility characteristics are the nigrosine, triphenylmethane, rhodamine, thio- L fiavine, auramine, quinone-imide, xanthane, sulphonated triphenylmethane, and nitro dyes. These include acid dyes, such as refer to the mono-, di-, and tri-sodium sulphonates of the nitro, azo, pyrazoline, quinoline, triphenylmethyl,

I diphenylnaphthyl methane, azine, xanthane, and

anthraquinone groups. Suitable pigments include water-dispersible blacks such as carbon black; white pigments, such. as .zinc oxide or titanium oxides; or? colored pigments, such as malachite green, iron blue, cadmium yellow, and the like. When pigments are used, they usually are dispersed as the discontinuous phase in suitable carriers, such as Water, resin solutions and the like.

The amount of dye in the ink formulation depends on the chemical nature of the coloring material used. Some dyes, even when used in small quantities, are capable of imparting sufficient color to lend legibility to the copy. With others, it is necessary to use higher concentrations of dye to secure the desired effect. The lower limit of the dye concentration, therefore, is determined by its tinctorial strength which varies widely from compound to compound. The upperlimit often is influenced by the solubility factors or by the eiiectof the dye on other ingredients of the ink-composition, as, for example, in causing gelation of the resinous material. We have found that 3 to 7 percent nigrosine WSJ is suitable for Water base stencil duplicating inks. Other dyes may be used in corresponding ratio although more or less may be used according to their characteristics, as pointed out above. When pigments are used, it is often desirable to use concentrations above 3' percent by weight with the upperlimit in the region of percent by weight or even more in some instances.

An important feature of Our invention resides: in the possibility of insolubilizing the body in gv agent upon drying to render the copy resistant to moisture and many of the hydrocarbons, chemicals and solvents, including oils, greases, alcohols, and other materials" with which the copy might come in contact. Insolubilization may be effected by reaction of the hydroxy or amino groups to form acetals, hemiacetals, cross linked polymers, or condensation reaction products the addition of aldehydes having latent reactivity and incapable of activation While in dilute-soluin contact with the copy. More rapid insolubilization may be secured by the use of more;

than 5 percent by weight glyoxal, and excellent results are secured by the use of amounts ranging from 0.5 to 2 percent. Pyruvic' aldehyde is illustrative of another suitable insolubilizing,

agent but it is less reactive than glyoxal and .rnay be used in higher concentration to accomplish a degree of insolubilization.

In order to increase the penetrabilityinto the impression paper and in order to improve the.

characteristics of the ink with respect to distribution through the ink pad and stencil, a wetting.v agent may be added to the composition. A. suitlable wetting agent may be selected from materials. such as the dioctyl esters of sodium sulfosuccinate. (Aerosols), quaternary ammonium. salts (Duponols) dibutylphenol sodium disuliionates (Areskelene) ,sulfonated ethers (Tensol) andlthe like. Less than 2 percent but more-than 0 .2 ercent of the wetting agent ordinarily is sufficient- -f to impart the desired wetting characteristic,- all though more may be used when desireda Y Another important feature of our new stencil duplicating ink composition comprises the addition of a humectant which reduces the e'vaporat, ing rate of the Water diluent and is compatible with the aqueous solution of the substance of high molecular weight. More important, the added humectant has the characteristic of modifying certain flow properties of the ink composition.

, Such modification is not necessarily measurable by viscosimeters operating at high rates of shear but exists, in fact, to the extent that leakage of the ink pad is greatly minimized and duplicator operation is substantially simplified. Under high shear, such as the forces developed by the Stormer Viscosimeter of the shearing forces operating while the ink is being forced through the stencil during duplication, the modified flow propertiesare not apparent and the ink flows as a liquid" having little additional viscosity. Polyhydric a1- cohols, such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycols, glycerine, polyglycols and polyalkylglycols and alkylolamines such as diethanolamine, triethanolamine, N-acetyl ethanolamine, N-formyl ethanolamine,

monoethanolamine sulpharnate, monoisopropanolamine sulphamate and the like exhibit these characteristics, especially with solutions containing hydroxy celluloses. Polyhydric alcohols are not readily volatilized and they remain after the waterhas been removed to flexibilize the adherent base. In a specific application, 1 to 25 percent by Weight may be used With hydroxy ethyl cellulose of medium viscosity While amounts up to 40 to 50 percent by weight may be used with the same material of higher viscosity grade. Corresponding amounts of other polyhydric alcohols with hydroxy ethyl cellulose or other high molecular weight substances may be used, the upper limit of concentration being that at which instability results. When more is used, there is a tendency to disturb the structure and stability of the colloid composition.

We prefer to use a polyhydric alcohol and a latent insolubilizing agent, such as an aldehyde,

in the same formulation. When so formulated, the aldehydric substance is able to react with the polyhydric alcohol and the high molecular Weight compound when constituted with hydroxyl or amino groups, the reaction being in the nature of condensation or acetalization to form acetals, hemiacetals, and cross-linked polymers or copolymers. Our invention also contemplates the use of one without the other. When the aldehyde is omitted, the ink still has some degree of water resistance because the polyhydric alcohol is capable of functioning as a protective agent.

Without limiting our invention to anyparticular composition, the following examples, given in parts by weight, will serve to illustrate suitable stencil duplicating inks embodying features of our invention:

Example I Percentage Material Nigrosinc WSI.

water solution at 20 0.). Dioctyl ester of sodium sulfosuccinate (Aerosol O'l). Ethylene glycol. Glyoxal (in 30 percent solution).

1. l0. 1. 67. Water.

' Viscosity, 130 Stormer seconds.

Polyvinyl alcohol (low viscosity grade) (4-6 cp. in 4% a Example II Example VIII Percentage Material Percentage Material 15. Carbon black in 40 percent aqueous dispersion (Aqua- 5. 0 Nlgroslne WSJ'.

black M). 1.0 Wetting agent. 1. O Alkyl aryl sulfonate. 45. 0 Urea-formaldehyde water soluble resin methylol 10. 0 Diethylene glycol. ureas). 1. 0 Glyoxal (in 30 percent solution). 2. 0 Glyoxal. 7. 0 Polyvinyl alcohol (medium viscosity grade) (20-26 op. 47. 0 Water.

in 4 percent water solution at 20 0.). 66. 0 Water. 100. 0

Viscosity, 100-120 Stormer seconds.

Viscosity, 110-120 Stormer seconds. Example IX Elia/"74313 III Percentage Material Percentage Material 5. 0 Nigrosine WSJ.

47. 0 Polyethylene glycol (6000 M. W.).

3.0 Glyorral (in 30 percent solution). 5.0 Nigrosine WSI (water soluble dye). l. 0 Wetting agent. 6.0 Hydroxyethyl cellulose (75-125 cp. in 5 percent Water 44. 0 Water. solution at 20 0.). 1.0 Dioctyl ester of sodium sulfosuccinate (Aerosol CT). 100. 0 10.0 Ethylene glycol.

0.5 Glyoxal (in 30 percent solution). 77. 5 Water. Viscosity, 100-140 Stormer seconds.

1 0 0 Glyoxal and pyruvic aldehyde are normally in- Viscosity, 100-120 Stornier seconds.

Example IV corporated in a water solution containing percent aldehyde; however, the amounts designated in the examples refer to dry weight of the free aldehyde. These materials may be combined in Percentage Material any order since they are generally miscible one Methyl cellulose (400 c. p. in 10 percent water solution Water.

blue the high molecular weight substance or bodying agent and water and then incorporate the other ingredients.

ments uniformly in the ink composition.

By the use of our new and improved stencil Viscosity,

When a pigment dispersion is used, it may be incorporated into the formulation with stirring to distribute the dispersed pigduplicating ink, drying takes place at a speed which is beyond that heretofore comtemplated for stencil duplicating inks, making it possible Percentage Material to handle the copy immediately. It is possible to eliminate setofi without the costly and cumbersome technique of slip-sheeting.

Galcocid Scarlet MOO (Water soluble dy Wetting agent (dioctyl ester of sodium sulfosuccinate).

Urea. Ethylene glycol. Vlater.

It is posimmediately. The ink produced by this invention dries rapidly on bond, ledger, card, or enamel stock, papers which have heretofore not been suitable for widespread use with stencil dup1icating machines, and it may be formulated to Example VI upon drying.

Percentage Material become insolubilized substantially immediately There are no materials present in such quantity to cause undesirable show through or Hydroxy ethyl cellulose (400-000 op. in 5 percent water solution at 20 C.). Water.

5 halo.

This is because the present carrier and v diluent is water which may be completely eliminated from the impression medium and is not resident as are the oils of prior duplicating inks.

It will be evident that other important advantages are derived from the use of water base stencil inks including the elimination of possible separation of the ink in use or prior to use Viscosity,

Percentage Material because the ink composition is stable; simplification in the processes of cleaning the machine and V stencil by the use of a simple water rinse as efiected by a dip or spray because the ink composition before transfer to the impression medio COO Carbon black in aqueous dispersion.

(Amber-lite PR-li). Water.

um is readily soluble in water and many of the common solvents; self-sealing characteristics dewith flow properties so related to rate of shear that inadvertent flow in the cylinder is eliminated without impairing the ability of the ink to pass through the stencil openings in the duplicating operation; and simplicity in ink manufacture because preparation is effected by solution which eliminates grinding or other tedious means for incorporating the colors and resinous material.

It will be understood that the basic substances may be prepared for marketing in concentrated or dry form to be diluted at the station of use with water before filling the ink container. It will further be understood that other miscible solvents may be partially substituted for the water as the diluent or diluting substance, such, for example, as the lower glyools, alcohols and the like. In addition, it will be understood that numerous substitutions may be made in the materials and their amounts without departing from the spirit of the invention, especially as defined in the following claims.

We claim as' our invention:

1. A stencil duplicating ink comprising an aqueous composition consisting essentially of Water as the diluent and carrier, a tinctorial agent, a wetting agent, a Water soluble resinous material constituted With groups selected from the groups consisting of hydroxy and amino and mixtures thereof to body the composition and to operate as an adherent base upon drying, a polyhydric alcohol soluble in the solution of diluent and resinous material and imparting a false body thereto, and a latent aldehyde from the group consisting of glyoxal and pyruvic aldehyde to insolubilize the resinous material upon drying.

2. A stencil duplicating ink comprising an aqueous composition consisting essentially of Water as the diluent, a tinctorial agent selected from the group consisting of water soluble dyes, water dispersible pigments and mixtures thereof, a wetting agent, a water soluble hydroxy reinous material to body of the composition and to operate as an adherent base upon drying, and a liquid polyhydric alcohol soluble in the solution of Water and the resinous material and present in amounts sufficient to impart false body to the composition without affecting the structure and stability of the colloid composition.

3. A base for stencil duplicating inks comprising a water dilutable composition consisting essentially of a tinctorial agent selected from the group consisting of water soluble dyes, water dispersible pigments and mixtures thereof, a wetting agent, a water soluble resinous material of high molecular weight capable of reaction with an aldehyde to an insoluble reaction product for bodying the diluted ink composition and operating as an adherent base upon drying, a liquid polyhydric alcohol soluble in the solution of water diluent and substance of high molecular weight, and an aldehyde selected of the group selected of glyoxal and pyruvic aldehyde to insolubilize the substance of high molecular weight.

4. A stencil duplicating ink comprising an aqueous composition consisting essentially of Water as the diluent, coloring matter persent in sufiicient quantity to impart legibility to the copy, a water soluble hydroxy resin of high molecular Weight to body the composition and to operate as an adherent base upon drying, a Wetting agent, a polyhydric alcohol that imparts a false body to the ink composition Without noticeably decreasing its fluid flow in high shear, and a latent aldehyde selected of the group consisting of glyoxal and pyruvic aldehyde to insolubilize the substance of high molecular weight upon drying.

5. A stencil duplicating ink, as claimed in claim 4, which contains less than 50 percent by Weight of the polyhydric alcohol.

6. A stencil duplicating ink, as claimed in claim 4, in which the resinous substance and the aldehyde are present in the ratio of about 2-20 to 1.

7. A stencil duplicating ink, as claimed in claim '7, in which the ingredients are present in the ratio of about 3 to 15 parts of the tinctorial agent, 3 to 25 parts of the resinous substance less than 50 parts of the polydric alcohol, 1 to 2 parts of the wetting agent, 0.5 to 2 parts of the aldehyde, and from 40 to parts of water.

8. A stencil duplicating ink as claimed in claim 4 in which the aldehyde is glyoxal.

THOMAS SEAL CHAMBERS. ROBERT THOMPSON FLORENCE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,385,613 Davis Sept. 25, 1945 2,510,257 Robinson June 6, 1950 FOREIGN PATENTS Number Country Date 356,403 Great Britain Sept. 10, 1931 592,210 Great Britain Sept. 11, 1947 OTHER REFERENCES Polyvinyl Alcohol, Copyright 1940 by E. I. Du Pont Co., pages 3 and 5. 

2. A STENCIL DUPLICATING INK COMPRISING AN AQUEOUS COMPOSITION CONSISTING ESSENTIALLY OF WATER AS THE DILUENT, A TINCTORIAL AGENT SELECTED FROM THE GROUP CONSISTING OF WATER SOLUBLE DYES, WATER DISPERSIBLE PIGMENTS AND MIXTURES THEREOF, A WETTING AGENT, A WATER SOLUBLE HYDROXY REINOUS MATERIAL TO BODY OF THE COMPOSITION AND TO OPERATE AS AN ADHERENT BASE UPON DRYING, AND A LIQUID POLYHYDRIC ALCOHOL SOLUBLE IN THE SOLUTION OF WATER AND THE RESINOUS MATERIAL AND PRESENT IN AMOUNTS SUFFICIENT TO IMPART FALSE BODY TO THE COMPOSITION WITHOUT AFFECTING THE STRUCTURE AND STABILITY OF THE COLLOID COMPOSITION. 